Intravenous (IV) administration sets which are useful for infusing medical treatment fluids to a patient are well known and widely used. In the most simple configuration, an IV administration set includes a fluid source, an IV line connecting the fluid source to the patient, and a device operatively associated with the IV line to influence the rate of fluid flow to the patient. In more advanced configurations, two sets are placed side by side to deliver two different medical fluids to the patient intermittently.
One such dual delivery system is conventionally termed a "piggyback" system wherein a primary set delivers a primary fluid and a secondary set delivers a secondary fluid to the patient sequence. The source of both the primary and secondary fluids, e.g. bags or bottles, are hung above the patient and linked to the patient by a network of tubing and valves which culminate in a common IV line to the patient. The primary and secondary fluid sources are positioned at a height differential so that delivery of one fluid is favored over the other, thereby imposing a pattern of sequential fluid delivery on the system.
The piggyback system may also include a device which regulates the rate of fluid flow to the patient. Flow rate control devices for the piggyback system are characterized as either pumps or controllers. Controllers rely on gravity for the flow of fluid through the system, while pumps exert an electro-mechanical force on the fluid to establish a fluid flow. U.S. Pat. No. 4,533,347 exemplifies a conventional piggyback system which employs a controller to regulate the flow of fluids to the patient. The controller is positioned downstream of the fluid sources on the secondary fluid line and the combined fluid line to regulate flow in both lines simultaneously.
Although effective, conventional piggyback systems have nevertheless been found to be somewhat restrictive and cumbersome in that they rely on a check valve and the height differential of the fluid sources to ensure the desired delivery sequence of the treatment fluids despite the concurrent use of a pump or controller. Accordingly, it is an object of the present invention to provide a secondary treatment fluid administration system which is operable in cooperation with a conventional primary treatment fluid administration set, yet which is not restricted to only a sequential mode of fluid delivery to the patient. It is further an object of the present invention to diminish reliance on the height differential of the fluid sources as a mechanism for sequential fluid delivery. It is another object of the present invention to provide a secondary treatment fluid administration system which provides a driving force other than gravity or electro-mechanical pumping to convey fluid through the system. A final object of the present invention is to provide control of the secondary treatment fluid administration system by means independent of the primary set.